A look back at how the 49ers-Seahawks rivalry became one of the fiercest in sports.

March 29, 2007: During an interview with CBS Sportsline's Dennis Dodd, new Stanford coach Jim Harbaugh opined that Pete Carroll's time at USC was winding down. "He's only got one more year." A miffed Carroll told the Los Angeles Times: "If he's going to make statements like that, he ought to get his information right. ... And if he has any questions about it, he should call me."

April 2: 2007: When reporters ask if Harbaugh had since called Carroll, the new coach responds: "I don't have any questions about his future ... said what I heard -- that he won't be there past the next year. We bow to no man. We bow to no program here at Stanford University."

Nov. 14, 2009: Stanford wallops USC 55-21 at the L.A. Coliseum. Harbaugh pads the margin of victory by going for a two-point conversion despite leading by 27 points late in the game. In the postgame handshake at midfield, Carroll asks Harbaugh, "What's your deal? What's your deal?" To which Harbaugh retorts: "What's your deal?"

Jan. 11, 2010: The Seattle Seahawks hire Carroll as head coach and vice president of football operations.

April 2010: Stanford offers fans a "What's Your Deal" ticket plan that allows fans a chance to package the USC game with two others on the schedule at a discount rate. All 1,081 packages sell out.

Jan. 7, 2011: The 49ers hire Harbaugh as head coach.

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Oct. 18, 2012: The 49ers defeat the Seahawks 13-6 at Candlestick Park. Two Seahawks later tell Yahoo Sports that Harbaugh taunted Seattle's team bus in the aftermath. "Yeah, he (honked at us)" safety Earl Thomas said. "It seems like he tried to be a professional in front of the camera, but he does his antics, like that, when cameras aren't around." Harbaugh calls the story a "fabrication" and said that he couldn't recall ever leaving the stadium while the opposing team's bus was still around.

Oct. 19, 2012: Harbaugh reveals at a news conference that he sent a letter to the NFL office questioning the Seahawks' rough play against the 49ers' offense. "I mean, it's physical play, is it in the rules? I think that's a good question: Is it in the rules? We have to ask that question and see where the interpretation is." Carroll said: "I thought our guys played really hard and tough, and they did too, and that was it."

Oct. 24, 2012: Cornerback Richard Sherman, who played for Harbaugh at Stanford, weighs in on the critique of physical play: "Sometimes, man, when the bully gets bullied, that's how that happens."

Dec. 23, 2012: On Harbaugh's 49th birthday, the Seahawks beat the 49ers 42-13 at CenturyLink Field -- and it could have been worse. Sherman approached Carroll on the sideline late in the game and told him to pour it on. "I'm not gonna lie to you," Sherman told Yahoo Sports. "I told Pete, 'Let's score and go for two.' He said, 'We have more class than that.' "

March 11: The Seahawks send their 2013 first-round pick (25th overall) and two other picks to the Minnesota Vikings for explosive receiver Percy Harvin. Hours later, the 49ers get veteran receiver Anquan Boldin from the Baltimore Ravens for a mere sixth-round draft pick.

June 11: Weeks after Seattle defensive end Bruce Irvin was suspended, Harbaugh is asked about the fact that five players from the Seahawks' 53-man roster have tested positive for performance-enhancing drugs since 2011. "I've definitely noticed it," Harbaugh said. "We want to be above reproach in everything and do everything by the rules. Because if you don't, if you cheat to win, then you've already lost, according to (late Michigan coach) Bo Schembechler. And Bo Schembechler is about next to the word of God as you can get in my mind."

June 13: A KJR (Seattle) radio host asks cornerback Brandon Browner for his reaction to Harbaugh's denouncement of the Seahawks' suspensions. "He's never going to be out there lined up against me. I wish he would. I'd put my hands around his neck," Browner said.

July 29: A Sports Illustrated cover story on Sherman ("The NFL's Most Voluble Player") recounts the fractured relationship the cornerback had with Harbaugh at Stanford. Sherman's father said his son's transition from receiver to defensive back saved him "because Richard didn't have to deal with Harbaugh anymore. They were out of each other's hair." When Harbaugh was asked in 2009 about Sherman's position switch, the coach said of the future All-Pro: "Don't know if he'll be able to beat anybody out over there or not."

Sept. 6: Harbaugh says he doesn't like the league's rules relating to hits on quarterbacks who run read-option plays. "I think it's flawed and a bit biased. ... I feel like you give a license now to players to hit quarterbacks at the knee or in the head."

Sept. 12: Carroll was asked if he, too, considers the NFL rules to be biased. "No. Not at all," he said. "I think the quarterbacks, when they're runners, they're able to get hit. And when they're not, they're not. That's the only way they could have stated the rules. I thought they were pretty clear about it."